AirHint found the following cheapest return flights from Austin (AUS) to Madrid (MAD) in September 2025 (see full year).

Return flights

30 Sep - 07 Oct	United
22 Sep - 30 Sep	British Airways
23 Sep - 30 Sep	Iberia
29 Sep - 06 Oct	United
25 Sep - 02 Oct	United
09 Sep - 16 Sep	United
22 Sep - 25 Sep	Frontier Airlines
17 Sep - 24 Sep	United
15 Sep - 10 Oct	Lufthansa
16 Sep - 11 Oct	Air Canada
07 Sep - 14 Sep	United
15 Sep - 22 Sep	United
05 Sep - 12 Sep	United
11 Sep - 18 Sep	United
13 Sep - 20 Sep	United

Also check the deals for one-way flights from Austin to Madrid in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Austin to Madrid in September from 492€

Return flights